PORTSMOUTH — The city must upgrade one of its wastewater treatment plants, according to a U.S. Environmental Protection Agency "consent decree," and it is going to cost tens of millions of dollars.

Dave Choate

Editor's note: This is the third in a series on the city's efforts to upgrade its wastewater treatment system. See Tuesday's Herald for a look at other wastewater treatment improvement projects in the city.

PORTSMOUTH — The city must upgrade one of its wastewater treatment plants, according to a U.S. Environmental Protection Agency "consent decree," and it is going to cost tens of millions of dollars.

No one involved in the process, from the EPA to the city, disputes those facts.

What remains up in the air is where the facility will be located and what level of nitrogen pollution, measured in milligrams per liter, will be allowed in the treated water leaving the plant. Both factors will drive construction costs, and whether building a new facility or upgrading an existing one is even realistic. Cost estimates range from $63 million to well over $100 million for a multitude of proposals for sites at either Peirce Island or Pease International Tradeport. City officials estimate the midpoint of that range would cause an estimated $1,400 jump in the sewer bills of city residents who are already concerned about tax increases in Portsmouth.

The state Department of Environmental Services is developing criteria for nitrogen levels, and Watershed Management Bureau Administrator Paul Currier said those should be complete before the city submits its final wastewater master plan in September. The EPA must sign off on the criteria, and environmental engineer David Pincumbe indicated the EPA is looking for municipalities to treat wastewater to the limits technology will allow, whenever possible.

Cost is the single biggest worry for Portsmouth. The city charges customers in Pease, New Castle and portions of Greenland and Rye the same rate it charges Portsmouth payers, something Deputy Public Works Director David Allen said is limited by state regulations, and can be raised only by 15 percent. An increase would require the city to go through a potentially lengthy process with the state Public Utilities Commission. He said large new projects such as the recently opened Residence Inn by Marriott are charged a capacity use surcharge that amounts to a "buy-in" fee, but that amounts to tens of thousands over the last couple of years and not the millions that would be necessary to help finance a new plant.

Short of additional revenues, officials said the city must figure out how best to introduce the rate increases that have made councilors and residents alike wary. Mayor Tom Ferrini said the council needs to take a look at ways to start increasing rates earlier in the process, so ratepayers aren't hit with one giant increase all at once.

"What are ways to lessen the impacts out in time? It is certainly prudent for us to model those impacts and consider what the ramp-up time might be," Ferrini said.

City Engineer Peter Rice said the city has the ability to absorb the amount of sewage currently put into the system.

"It's not a capacity issue," he said.

Enter the Peirce Island wastewater plant, a fixture on the island since 1964. Upgraded three times over the last 4½ decades, the plant has the capacity for some 4.8 million gallons of waste and stormwater per day. It would need to be upgraded from enhanced primary treatment, which involves retention of sewage, separation of solids and liquids and chemical treatment, to at least secondary treatment, typically involving the use of bacteria to further break down and treat the waste.

An expansion there would require two new buildings, which would have to be built upward or force a waiver for a shoreline protection setback. The type of system in use there, which uses biological membranes that filter out solids and large particles, is expensive and has a notoriously short shelf life, according to Peter Goodwin, of city consultant Weston and Sampson. Space constraints on the island mean a phased construction would be difficult at best, according to Rice.

Cost to replace that facility depends on whether the city will be treating water to achieve 8, 5 or 3 milligrams per liter of nitrogen, levels the EPA and N.H. DES are mulling. Rice and Allen acknowledge nitrogen has an impact on the environment, but said it has become the EPA's culprit of choice despite a host of other factors, such as turbidity (caused by suspended solids), that are also damaging the Piscataqua River watershed. Currier previously estimated somewhere between 20 and 30 percent of the watershed's nitrogen issue is caused by "point sources" such as wastewater treatment plants, with the rest from "nonpoint sources" like septic leaks and fertilizer runoff.

Pincumbe said every plant in the Great Bay watershed will face tightening of restrictions on a case-by-case basis, adding the EPA hoped it would be at the limit of currently available technology.

"We certainly recognize that getting to the limits of technology will be expensive, and there will also be a need to address nonpoint sources," Pincumbe said. "How we integrate the two and over what time frame are the real issues that need to be worked out."

There's also the Pease facility, a secondary treatment plant that currently serves the tradeport only, but could be expanded to handle the city's sewage load, with a stripped-down Peirce Island facility available as backup in wet weather. However, stricter nitrogen requirements might make locating that plant's outfall further upriver impossible, given concerns that it will affect a greater part of the Piscataqua.

The city has not shied away from stating its preference for the Pease expansion as a potentially less expensive option and one that would allow more of Peirce Island to be used by city residents. An alternative option to pump wastewater from the plant to the Peirce outfall is estimated to cost $119 million.

Because the facility's current capacity is only a fourth of the Peirce Island plant's at 1.2 million gallons per day, a new discharge permit would be required to increase the allowable flow. Rice said it would be likely that a discharge at the current Pease site would require a standard of 3 milligrams per liter because it is located further upriver than the Peirce Island facility.

In either case, the city is pushing to be allowed to phase construction. Rice and Goodwin both said it will allow the city better financial flexibility and lessen the immediate impact to ratepayers, who they acknowledged would be hit hard when sewer bills rise because of the project.

"Phased construction can buy you some time," Goodwin said last month.

Construction is still likely years away, however. If and when a plan is approved by the EPA, Rice said it will need to go through value engineering and serious vetting before it begins to take its final shape.

Shellfish sellers and town officials in Eliot, Maine, have expressed concern over a Pease location's effect on their business. Elizabeth O'Donoghue, chairwoman of the Eliot Board of Selectmen, raised concerns earlier this year when it was revealed that Pease was a serious contender for a location.

The two main concerns are with shellfish beds, which O'Donoghue and others fear will be affected by wastewater, and the fact the outfall is located more or less directly across from the boat launch and only public beach in Eliot. The town has received a letter from the city acknowledging the concerns, she said, and Eliot is awaiting a decision as to whether the plant expansion happens at Pease or Peirce Island.

"When they make up their minds, we can swing into action," she said. "We're not going to fight until we know what we're fighting."

David Mullen, executive director of the Pease Development Authority, said any decision would require the board's consideration and a consultation with the Federal Aviation Administration.

"We haven't had to entertain any discussion of expansion as yet," Mullen said.

The city plans to turn in proposals for both plant locations Tuesday, June 1, the deadline under the EPA's consent decree for a draft wastewater master plan. Without an exact number in hand but with a deadline fast approaching, Rice admitted to frustration but said the city is moving ahead as best it can.

"We haven't said 'Stop, we're not going to do anything to resolve this.' The EPA has been difficult to nail down, but we would do it without having the proverbial gun to our heads," he said.

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